A distributed parameter model of the Janus-Helmholtz transducer.

The Janus-Helmholtz (JH) transducer is a low-frequency, high-power, broadband underwater transducer type. Numerous studies have shown the effectiveness of the finite element method (FEM) in designing JH transducers and predicting their electroacoustic performance. However, a precise theoretical model for JH transducers has not yet been proposed, and the modal identification problem of JH transducers remains unsolved. In this paper, a distributed parameter model (DPM) of the JH transducer is proposed, which consists of the DPM of a Janus transducer and the DPM of a cylindrical liquid cavity under elastic wall conditions. By comparing the DPM with FEM, it is confirmed that the DPM can accurately calculate the resonant frequencies, admittance, amplitude, and phase of vibration velocity of the JH transducer. Additionally, a physical analogy is introduced to reveal the relationships between the transducer's resonances. Two JH transducers with different liquid cavities are fabricated and tested, and the results from the DPM, FEM, and experiments exhibit good agreement. The DPM can not only provide valuable theoretical support but also significantly reduce much time in designing JH transducers. Furthermore, it may inspire further advancements in adjusting the resonant frequencies or expanding the working bandwidth of JH transducers.